Electric controlling apparatus



Nov. 8, 1949 A. M. COHEN 2,487,313

ELECTRIC CONTROLLING APPARATUS Filed March 7, 1946 2 SheetsSheet l @5 77//l l// //l IN VEN TOR.

Nov. 8, 1949 A. M. COHEN ELECTRIC CONTROLLING APPARATUS 2 Sheets-Sheet 2Filed March '7, 1946 INVEN TOR. 4/777/d/7/Z 6 06 5 ia A Patented Nov. 8,1949 ELECTRIC CONTROLLING APPARATUS Arthur M. Cohen, New Rochelle, N.Y., asslgnor to Ward Leonard Electric Company, a corporation of New YorkApplication March 7, 1946, Serial No. 652,521

14 Claims. 1

This invention relates to improved electromagnetic controllers and toregulators for maintaining constant the voltage, or other variablefactor, of a dynamo-electric machine.

One object is to provide a compact form of controller which will occupysmall space and which is particularly adapted for controlling smallunits, although it may be utilized for controlling units of largecapacity. Another object is to produce a controller of high sensitivityand which-is capable of securing close regulation. Another object is toavoid the objections of a vibrating type of contrailer and to provideregulation by a series of steps which will insure long life and requirelittle or no attention and avoid objectionable sparking anddeterioration of the control contacts. Another object is to provide animproved form of structure and relationship of the various parts forsecuring the above mentioned results, various features of which may beutilized for control purposes other than the particular example hereindisclosed. A further object is to provide means for compensating fortemperature changes and thereby insure maintenance of the control withinclose fixed limits regardless of temperature changes. A further objectis to mount the variable resistance device and resistive elements inclose relation to the controlling magnet with common supporting parts toform a complete unitary structure. Other objects and advantages will beunderstood from the following description and accompanying drawingswhich illustrate a preferred embodiment of the invention.

Fig. 1 is a front elevation, the enclosing box being removed except thelower portion of the box; Fig. 2 is an end view looking from the rightof Fig. l and showing portions of the enclosin box; Fig. 3 is ahorizontal section on the line 3-3 of Fig. 1; Fig. 4 is an end viewlooking from the left of Fig. l, the prong base not being shown; Fig. 5is a face view of the fingers which variably engage the contacts towhich the resistive elements are connected; Fig. 6 is a face view of thepivot spring, plunger guide and finger controlling bar looking from theleft of Fig. 1; Fig. '7 is a top side view thereof; Fig. 8 is an endview thereof; and Fig. 9 is a diagram of electrical connections.

Referring to Fig. 1, the axis of the magnet coil to is horizontal. Themagnet frame is formed of two L-shaped sheet iron strips fitted togetherat I their meeting edges. One strip ll embraces the top and left-handend of the coil and the other strip Ila embraces the bottom andright-hand end of the coil. A base [2 of insulating material havingconnecting prongs l2a is located below the magnet and is secured to thebottom l3 of a sheet metal enclosing box preferably made of hardaluminum. The prong base is of the usual radio connecting type. A screwl3a at each side passes upwardly through the prong base and bottom coverand has a threaded engagement with the bottom of the magnet frame forholding the parts together.

Referring to Fig. 3, a hollow cylindrical plug it of iron is welded atits outer end to the frame portion Ila and extends partially within thecoil [0. In addition to forming a path for the magnetic fiux, it servesas a stop for the magnetic plunger It in its movement to its unattractedposition. A washer l6 of magnetic material is welded to the outer sideof the frame II and serves as a stop for the plunger in the fullyattracted position. The plunger is yieldably supported and alignedcentrally within the coil by means comprising two metal plates I1 and Naof hard aluminum or other non-magnetic material. This supporting meanswill be later described. A spacing tube [8 of brass extends from theinner end of the plunger to the plate Ila. A spring 1 cup l9 preferablyof aluminum, engages at its central projecting portion, the plate l'la.A tube or eyelet 20 of brass extends through the plunger and spacer l8and through the guidingsupports l1 and Ila. The left-hand end of theeyelet is turned over the outer surface of the plate IT. The right-handend of the eyelet extends through and is turned over the spring cup ill.The eyelet thus holds these parts firmly together as a movable assembly.

A coiled compression spring 2! seats against the spring cup 19 at itsinner end and against a metal ring 22 at its outer end. The springbiases the plunger towards its unattracted position. The ring 22 isprovided with three outwardly extending projections 22a, as shown inFig. 2, which extend through inclined slots 23a, shown in Fig. 1, of afixed metal end cup 23. Thus by turning the ring 22, the spring 2| willbe more or less compressed for adjusting the voltage, or other factor,

- which the regulator is to maintain substantially constant. The upperprojection 22a is extended and bent to engage a slot 23b in the end cupfor convenient adjustment. The upper edge of this slot is notched andengaged by an upset projection on the extension 22a for holding the ringfixed in any adjusted position.

Mechanical damping means for the plunger are provided by a combinedspring and dashpot relationship. The dashpot cylinder 24 is shown inFig. 3 and is fixed in position by being riveted at its center to theend cup 23. The piston which may be of carbon material, is provided witha central eyelet to which is soldered one end of a spring rod 26preferably of phosphor bronze. This rod extends through the long eyelet20 and is soldered at its left-hand end to the end of this eyelet. Theportion of the rod in the space adjoining the plunger is S-shaped. Thiscombined clamping means has a double acting effect. Upon any change inthe exciting current of the magnet, the resilient rod 26 permits theplunger to move quickly to its new position'giving-a rapid correctiveresponse to the controlling means and then the piston is moved lessrapidly in following up the movement of the plunger. It thus steadiesthe movement of the plunger in attaining any adjusted position whilepermitting high sensitiveness of response.

All the parts are held together by four through studs or posts 21, oneat each corner. They pass through outwardly extending portions of theend cup 23 as shown in Fig. 2, through spacing sleeves 21a and throughfour corners of the magnet frame and coil spacing sleeves 21b. Thesepins or studs also pass through other parts, later explained, and allthe parts are thus held in fixed proper relation by the spacing sleevesand stud nuts and washers.

The yieldable aligning support of the left-hand end of the plungerassembly is shown in Figs. 6, 7 and 8. The previously referred tosupporting plate I1 is shown as-having a hole ill) for receivin the endof the eyelet 20. The right-hand end of the plate is secured by a pairof rivets to the outer side of a hollow rectangular shaped thin phosphorbronze spring 28, the plate I'I extending within the hollow centralspace of the spring. The rear end of the spring, or left-hand portionlooking at Fig. 6 is secured by a pair of rivets to a metal strip orbracket 29. This bracket is provided at its ends with holes for thepassage of the two rear holding studs 21 for supporting the bracketfixed in place by clamping nuts and intervening lock washers. Thealigning plate Ila of the plunger assembly at the right-hand end issimilarly supported by a hollow rectangular leaf spring 28 and bracket29 but its bracket is supported on the two front studs, as well shown inFig. 1, being reversely supported with reference to the left-hand one.Thus .upon any movement of the plunger assembly, the

aligning support of the two end portions will maintain and guide theassembly in axial align ment while the springs permit yieldable movementupon slight change of the exciting current.

Again referring to Figs. 6, 7 and 8, the left-hand yieldable guideaccomplishes a further function of adjusting the step-by-step control ofthe variable resistance device. For this purpose there is secured to themovable end portion of the spring 28, a finger controllin bar 30. Thisis formed of a thin sheet of metal bent to the form shown. A reducedcentral end portion 30a is bent to extend under the end portion of thespring and is secured thereto by the pair of rivets which also hold theplate 11, there being mica sheets or washers 3| introduced on oppositesides of the portion 30a for insulating the bar. The bar is bent atright-angles to the rear portion 30a and extends a short distanceoutwardly and then is bent inwardly to form the portion 301). As shownin Fig. 8 the part 3% is bent further along its length to form two partswhich diverge from the middle, forming a wide obtuse angle between them.The purpose of this will be explained later.

Referrin to Fig. 4, a rectangular plaque, or

plate, 32 of a thin sheet of mica is supported at its four corners bythe studs 21 and fixed in position by spacing nuts and washers. At therighthand portion of the plaque is supported a vertical row of contacts33 projectin from its inside face as shown in Fig. 1. These contacts arepreferably made of a silver platinum compound with rounded endsprojecting inwardly and having reduced shanks projecting outwardlythrough the mica plaque. Each shank is split longitudinally and thedivided portions spread apart against the outer face of the plaque forclamping the contacts in fixed position. The resistive conductors 34 areconnected to the contacts 33 and are located on the front face of theplaque, being connected to the contacts by the clamping shank portionsand by soldering. These resistive conductors have no insulating coveringand thereby can stand high temperatures. They are held in spacedposition on the face of the plaque by passing from the contacts underprojections 32a formed on the left-hand edge of the plaque. Anadditional pair of similar contacts 33a are provided and similarlymounted to form terminals, the terminal leads 35 being connected tothese terminals by soldering to the projectin portions on the inner sideof the plaque. The circuit from one lead to the other through theresistive conductors may be followed from the lower lead 35 through thelower resistive conductor 34 to its contact, then through anotherresistive conductor to the next upper contact and so on successively tothe contact next to the top, then through the upper resistive conductor34 to the upper terminal. The

' upper and lower' conductors 36 connecting the terminals to the upperand lower contacts 33 respectively have no appreciable resistance. Theresistivity of the resistors 34 are graduated, the outer'on'es havingthe lowest resistance and the inner ones having the highest resistancebetween contacts. It is obvious that when all of the contacts arebridged by a low resistance conductor, all of the resistive conductorsare short-circuited and the controlled circuit is in a resistance-alloutcondition. When all except the upper and lower contacts areshort-circuited, the upper and lower resistive conductors are insertedin the controlled circuit. Continued removal ofthe shortcircuit towardsthe middle of the contacts, gives a step-by-step removal of resistance;and when all short-circuiting of the contacts is removed, all of theresistance will be included in the controlled circuit.

There is another resistive conductor 31 mounted on the mica plaque. Thisis connected between additional terminals 38 from which leads 39 extend.The resistive conductor 31 is positioned on the inner side of the plaqueand is held in place by being looped over projections 32b formed in theupper and lower edges of the plaque. This resistive conductor is formedof a material having no appreciable temperature coefllcient ofresistance, such as an alloy of nickel and chromium, or of nickel andcopper. Its purpose will be explained later.

Fig. 5 shows a face view of the variably controlled spring fingers orresilient contact strips for variably short-circuiting the resistiveconductors 34. This is a thin sheet of heat treated spring material suchas phosphor bronze, or beryllium copper. The fingers 40 extend from acommon connecting base portion 40a. This base portion is covered by aclamping metal strip M of the same size as the base. A pair of rivets 42pass through the strip 4 I, the base portion and the mica. plaque forholding these parts together.

Thus the resilient fingers 40 extend from the left-hand portion of theplaque on its inner side; and the right ends of the fingers are springpressed against and respectively engage the contacts 33. The inside faceof the fingers and base portion are overlaid with a coating of goodconducting and contacting material such as an alloy of silver andplatinum.

The function of the finger controlling bar 30b will now be understood.The ends of the fingers 40 extend a short distance beyond the contacts33 and the inclined side portions of the bar extend over these ends.When the magnet is deenergized, the biasing spring 2| forces the plungerand bar 30b to the left as shown in Fig. 1. Underthis condition the bardoes not engage any of the fingers and all of the resistive conductors34 are then short-circuited. when suificient current passes in themagnet winding, the plunger and bar 30b will be moved slightly to theright and the upper and lower ends of the bar will draw the upper andlower fingers away from their contacts, thus inserting the upper andlower resistive conductors 34 in the controlled circuit. Furthermovement causes the next inner pair of fingers to be separated fromtheir'contacts and thereby insert another pair of resistive conductorsand so on until in the limiting attracted position all of the resistiveconductors are inserted in the controlled circult. In practice theplunger will assume a position determined by the value of the magnetcurrent and change slightly according to any slight change of current toincrease or decrease the inserted resistance. Thus 'a high degree ofsensitivity and refinement of control are obtained. A further refinementof control is obtained by slightly inclining one side of the finger barmore than the other so that a staggered successive action is obtained inthe control of the fingers first on one side of the bar and then on theother, giving successive control oi! each resistive conductor 34,instead of a pair at a time.

There is another resistive conductor 43 shown in Fig. 1 located in thespace between the magnet winding l and the lower part of the magnetframe. This has a negative coefiicient of resistance such as a carbonblock. It is in the form or a small fiat plate with conductor leadssecured to its opposite edges and is, as later explained, connected tosecure compensation for changes in temperature of the regulator.

In practice these regulators have been built to have overall dimensionsincluding the enclosing box and excluding the prong base of about twoinches long, one-and-five eighths inches high and one-and-a-quarterinches deep and have secured close regulation under widely varyingspeeds of the dynamo-electric machine.

Fig. 9 shows the electrical connections of one application of theinvention to the voltage control of a variable speed generator, such asa hand driven generator. The small circles designated A to H representthe prongs lZa of the prong base. The parts indicated within the prongsA to H represent the parts of the regulator already described and arecorrespondingly numbered. The parts shown outside the prongs A to H areconnected to the usual prong socket; and the diagram shows theconnections when the prongs are inserted in the socket. The armature 44of the generator is shown connected at one terminal to ground and at theother terminal to the prong B. The field winding 45 oi the generator isconnected from the ground side of the armature to the prong G. Prongs B,C and D are directly connected together by leads on the upper side ofthe prong base, there being more prongs than necessary in the standardprong base. Prongs E and F are similarly connected together and likewiseprongs H and A.

The magnet coil I0 is connected at one terminal to ground by prong A.The other terminal is connected to prong F and then through resistivedevices 31 and'43 in parallel to prongs C and B and thence to theungrounded side of the motor armature. The magnet coil is thus subjectedto the armature voltage. The variable resistors are connected in serieswith the generator field winding by a circuit from oneside oi thegenerator armature through the field winding to prong G, then throughthe resistors to prong B and to the other side of the armature.

When the generator is not running, the plunger of the regulator isbiased by spring 2| to cause the short-circuiting of all the resistors34, as already explained; and when in operation the regulator will varythe resistance of the field circuit to maintain the generator voltagewithin close limits. Compensation for changes in temperature of theregulator is provided for by the parallel connection of the resistors 31and 43 in series with the magnet coil l0. Otherwise increase intemperature would reduce the voltage maintained at the armatureterminals due to increase in resistance of the magnet coil and of theresistors 34. The compensation is secured by reason of the fact that anyincrease in temperature will not materially affect the resistance of theresistor 31 but will decrease the resistance of the resistor 43. Thispermits a proper amount of increased current to pass through theresistor 43 and through the magnet winding l0 and thereby short-circuita correspondingly increased amount of the resistors 34 to compensate forthe temperature increase. Upon decrease of temperature, the reverseaction takes place.

It is apparent that this improvement results in the production of aregulator unit having all the parts closely related in compact formwhich mutually cooperate to produce the desired results.

Although a particular embodiment of this invention has been shown anddescribed, it will be understood that various modifications may be madewithout departing from the scope thereof.

I claim:

1. Electric controlling apparatus comprising a supporting plate, aplurality of resistors mounted on one side thereof, an aligned row offixed insulated contacts positioned on the opposite side of said plateand between which said resistors are respectively connected, resilientcontact fingers biased to engage said fixed contacts respectively forshort-circuiting the fixed contacts, said fingers being mounted andsupported on the said opposite side of said plate, and a movable barhaving a surface inclined to said aligned fixed contacts for engagingsaid fingers to successively move said fingers from engagement with thefixed contacts.

2. Electric controlling apparatus comprising a supporting plate ofinsulating material, a plurality of bare resistive conductors mounted onone side thereof, an aligned row' of fixed contacts positioned on theopposite side of said plate and between which said resistive conductorsare respectively connected, resilient contact fingers biased to engagesaid fixed contacts respectively for short-circuiting the fixed.contacts, said fingers being'mounted and supported on the said oppositeside of said plate, and a movable bar having a surface inclined to saidaligned fixed contacts for engaging said fingers to successively movesaid fingers from engagement with the fixed contacts.

3. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a movable plunger, a support of insulatingmaterial mounted on an end portion of the magnet frame, an aligned rowof fixed contacts on said support, resilient contact fingers mounted onsaid support biased to engage said aligned contacts respectively, and amovable bar having a surface inclined to said aligned contactsforsuccessively engaging said fingers to successively move the fingersfrom engagement with the:

aligned contacts, said, bar being mechanically connected to saidplunger.

4. Electric controlling apparatus comprising an electromagnet having amagnet frame, .a winding and a movable plunger, a support of insulatingmaterial mounted on an end portionof the magnet frame, an aligned rowof-fixed contacts on said support, resilient contact fingers mounted onsaid support biased to engage said aligned contacts respectively, amovable bar having a surface inclined to said aligned contacts forsuccessively engaging said fingers to successively move the fingersfrom-engagement with the aligned contacts, said bar being mechanicallyconnected to said plunger, and a yieldable support mounted on said endportion of the magnet frame between said first named support and saidend portion of the magnet frame for yieldably guiding said bar andplunger.

5. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a movable plunger, a support of insulatingmaterial mounted on an end portion of the magnet frame, a plurality ofbare resistive conductors mounted on said support, an aligned row offixed contacts mounted on said support and between which said resistiveconductors are respectively' connected, resilient contact fingersmounted on said support biased to engage said aligned contactsrespectively, and a movable bar having a surface inclined to saidaligned contacts for successively engaging said fingers to successivelymove the fingers from engagement with the aligned contacts, said barbeing mechanically connected to said plunger.

6. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a plunger, supporting posts extending fromsaid frame, a plate of insulating material supported on said posts, analigned row of fixed contacts on said plate, resilient contact fingersmounted on said plate biased to engage said aligned contactsrespectively, a movable bar having a surface inclined to said alignedcontacts for successively engaging said fingers to successively move thefingers from engagement with said contacts, said bar being mechanicallyconnected to said plunger, and a yieldable support mounted on said postsbetween said plate and said frame for yieldably guiding said bar andplunger.

7. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a plunger, supporting posts extending fromsaid frame, a, plate of insulating material supported on said posts, aplurality of bare resistive conductors mounted on said plate, an alignedrow of fixed contacts on said plate between which said resistiveconductors are respectively connected, resilient contact fingers mountedon said plate biased to engage said aligned contacts respectively, amovable bar having a surface inclined to said aligned contacts forsuccessively engaging said fingers to successively move the fingers fromengagement with said contacts, said bar being mechanically connected tosaid plunger, and a yieldable support mounted on said posts between saidplate and said frame for yieldably guiding said bar and plunger.

8. Electric controlling apparatus comprising an. electromagnet having amagnet frame, a winding and a plunger, a dashpot for retarding themovement of the plunger, and a resilient connection between the plungerand the piston of the dashpot.

9. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a plunger, a dashpot for retarding themovement of the plunger, a coiled spring outside'the cylinder of thedashpot for biasing the plunger in one direction, an enclosure aroundsaid spring, and a ring at one end of said spring having projectionsextending through inclined slots in said enclosure for adjusting theforce exerted by the spring on the plunger.

10. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a plunger, a variable contact devicecontrolled by movement of the plunger fixed to an end portion of theframe, a dashpot for retarding the movement of the plunger fixed to theopposite end portion of the frame, and a prong base fixed to a sideportion of the frame, the prongs of said base being electricallyconnected to said device and said winding.

11. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a plunger, 5. variable contact devicecontrolled by movement of said plunger, and a pair of resistorsconnected in parallel with each other and in series with said windingfor compensating for change in temperature, one of said resistors havinga negative temperature coefiicient of resistance and the other of saidresistors having approximately no temperature coeflicient of resistance.

12. Electric controlling apparatus comprising an electromagnet having amagnet frame, a winding and a plunger, a variable contact devicecontrolled by movement of said plunger, a pair of resistors connected inparallel with each other and in series with said winding forcompensating for change in temperature, one of said re sistors having anegative temperature coemcient of resistance and the other of saidresistors having approximately no temperature coeflicient of resistance,and an enclosing casing for all of said apparatus.

13. Electric controlling apparatus comprising an aligned row of fixedcontacts, resilient movable contact strips biased to engage said fixedcontacts respectively at one end portion of each of said strips, saidresilient strips being electrically connected together at their otherend portions, and a movable bar having a surface inclined to saidaligned fixed contacts for engaging said movable contact strips tosuccessively move the movable contact strips from engagement with thefixed contacts.

14. Electric controlling apparatus comprising an aligned row of fixedcontacts, resilient movable contact strips biased to engage said fixedcontacts respectively at one end portion of each of said strips, saidresilient strips being electrically connected together at their otherend portions, and a movable bar having two surfaces inclined to eachother at an obtuse angle and also inclined to said aligned fixedcontacts for successively engaging said movable contact strips tosuccessively move the movable contact strips from engagement with thefixed contacts, the said inclination of the two surfaces extending inopposite directions from the middle of the movable bar along its length.

ARTHUR M. COHEN.

REFERENCES crrEn The following references are of record in the file ofthis patent:

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